
As long as the equation in question can be expressed as the sum of the three equations with known enthalpy change, its
can be determined with the Hess's Law. The key is to find the appropriate coefficient for each of the given equations.
Let the three equations with
given be denoted as (1), (2), (3), and the last equation (4). Let
,
, and
be letters such that
. This relationship shall hold for all chemicals involved.
There are three unknowns; it would thus take at least three equations to find their values. Species present on both sides of the equation would cancel out. Thus, let coefficients on the reactant side be positive and those on the product side be negative, such that duplicates would cancel out arithmetically. For instance,
shall resemble the number of
left on the product side when the second equation is directly added to the third. Similarly
Thus
and

Verify this conclusion against a fourth species involved-
for instance. Nitrogen isn't present in the net equation. The sum of its coefficient shall, therefore, be zero.

Apply the Hess's Law based on the coefficients to find the enthalpy change of the last equation.

Answer:
0.416666667
Explanation:
number of moles= mass of sample ÷ molar mass
=5÷12
=0.41666667
The answer is:
B. orbits closer to its parent planet that the most other moons
That is because in Neap Tides, Spring Tide, Lunar Eclipse, Solar Eclipse, and other thing you always see the Moon orbiting the Earth in diagrams.
Answer:
The Earth formed billions of years after the Universe formed
Explanation:
The "universe" is said to have been formed <em>billions of year ago</em> through an explosion. This was called the <em>"Big Bang Theory." </em>This lead to the<u> expansion of the universe</u> owing to its high temperature and density. After which, the universe cooled down. Galaxies and stars were then formed. Some of the stars died due to explosion, which then led to the <u>creation of planets</u>. Such formation of the planets happened around <u>4.5 billion years ago.</u> This is <em>9.3 billions of years later</em> than the universe was formed<em> (13.8 billions of years ago)</em>. So, this explains the answer.